I've heard of vaping, but "juuling" is new to me. If you're now sure what "juuling" is, it's basically a form of vaping often difficult to detect. We've heard from principals about the many challenges vaping presents in schools, one of the main ones being, you have no clue what's being vaporized and ingested.
To get you up-to-speed, watch the embedded video from PBS News Hour and read EdWeek's article,
Juuling and Teenagers: 3 Things Principals and Teachers Need to Know.